It is not mandatory for you to use your real name and surname if you do not want to, so you can choose whatever pseudonym you want, as long as it does not match a real person (famous) or a trademark.

All contents that you post (or link) that are your property remains your property in every way. No use can be made of it without your consent by anyone. ( this is not facebook ! ;)

This instance is not supposed to be a personal website/portfolio, so it is not a place to archive your works/pictures/etc.
For this purpose, you should definitely get(or create) a real website.
Mastodon is a social tool, like email, except that it’s not used the same way. Even if some people are using facebook or twitter like a place that belongs to them, that is not true ! And a lot of them have had an unpleasant wake up call when they have been kicked out of the network for obscure reasons.
Of course, I don’t plan to kick anyone out, but I am not crash proof, so think about it. (Even if I have done my best to anticipate troublesome situations to be able to restore a working instance without too much pain ;)

If you so desire it, you can join another instance at any time, export the list of users that you are following, and redirect your actual account to the new one. The redirection will be effective for one year only. After that period of tme your followers will probably be up to date so your account will be deleted.

For now, there’s no way to export all the data of your account (if you move to another instance for example). The only thing that you can export is the list of users that you’re following, and that’s it.
I doubt that it will be available soon because it seems quite complex (logic wise) to get that working considering the very nature (decentralized) of mastodon.
If you move to another instance, your previous “toots” are linked to the previous instance, and so they can’t fit on another one. It is a bit like changing your email address and asking all of your contacts to modify their archived email messages to match your new address. No can do !

On this instance, the exif information of your images will not be stripped down, because when it comes to ownership/creator informations, stripping them down is like using an image editing software to erase a copyright note.

If you do not want to share your exif information, you can always strip them down yourself, that is pretty easy (with xnview for example), or even better if it's that much of a concern for you: you can prevent the software/device to create them in the first place !

Generalistic instance that is art friendly. Goofy people are welcome !